This invention relates to an improved method and apparatus for receiving and transmitting data signals over a multi-port optical node.
In recent years, the Cable Television (xe2x80x9cCATVxe2x80x9d) industry has been extending its traditional mandate by providing new television-based entertainment applications to even more and more subscribers. The new applications include for example, broadband telecommunications, interactive multimedia, and video on demand (xe2x80x9cVODxe2x80x9d). As the variety of new applications and the number of subscribers continue to increase, the distribution systems for CATV plants (the physical implementation of the system) must be continually modified and upgraded. To handle the growth, the CATV equipment must be reliable and rapidly configurable. Such growth has led the CATV operators to change the implementation of distribution systems from an all coaxial tree-and-branch architecture to the multi-port optical node design used, for example, with fiber optic networks.
Optical nodes are the point of connection and conversion between the fiber optic cable and coaxial cable of a distributed network. The data from the headend service provider is usually sent over the fiber cable of the network to a plurality of preconfigured optical nodes for broadcast via the coaxial cable into a plurality of homes serviced by each of the optical nodes on the network. Depending on network architecture, each optical node has a plurality of ports for providing a direct connection between the optical node and the external network for converting an optical signal back to a Radio Frequency (xe2x80x9cRFxe2x80x9d) signal for distribution in the CATV coaxial plant.
The major components of an optical node include an optical receiver which receives information-modulated light from an optical fiber and converts that information into an electrical signal, an optical transmitter which converts electrical signals that originate from the subscriber to information-modulated optical signals that are transported by optical fiber to a central location, a RF amplifier which provides additional gain and filtering for the electrical signals for distribution to subscribers, and a power supply which receives AC/DC electrical power for the optical node from the main cable or through a dedicated power line.
The typical optical node has its major components configured among electronic modules, fixed into specific slots in the node. The most prevalent optical node configuration in the market today has a total of four to six RF ports on the left and right sides of the optical node and which are serviced by a single RF amplifier module. One of the limitations of this configuration is that in the event of a failure of the circuitry driving one of the four ports, all four ports need to be removed from service to replace the offending RF module. As CATV delivery system reliability becomes increasingly important to be competitive with other telecommunication service providers, the up time of a system, as well as the number of subscribers affected by a given outage of service, become mission critical.
Another critical shortcoming with typical optical node implementation today is the ability of the system operators to have optical nodes that are field configurable. When modules are preconfigured and fixed into slots in an optical node, system planners have limited flexibility in how to configure the cables leading to the ports. A variety of environmental and space factors control how a node is ultimately installed at a location. This lack of flexibility in where the ports are on the node causes difficult installation requirements and, therefore, increases installation time. Little or no flexible expansion or configuration capability is typically available for an optical node installation today.
In yet another limitation of a typical configuration of an optical node, the electronic modules and slots of the optical node lack uniformity in size. Thus, electronic modules are limited to the slots of the node specifically built to house that particular module. This limits the system operator""s ability to configure optical nodes for future expansion and forces them to over-configure individual nodes or add more nodes to the distribution network, both costly alternatives.
In still yet another limitation of a typical configuration of an optical node, power supplies that are rated for a fully loaded version of the optical node must be configured for each optical node. While this serves the long-term plans of a system build, the system operator is forced to buy much more capacity than is necessary for his short to intermediate term needs.
Therefore the intention of the present invention addresses inherent problems with current optical node design and deployment and presents the solution in a multi-port optical node that is scaleable, highly modular, and field configurable.
In accordance with the present invention, an improved multi-port optical node is described.
The optical node is integrated into a data distribution network with the optical node configured to send and receive data of the distribution network. The optical node comprises a main housing. The main housing provides environmental protection and a thermal path to the ambient environment sufficient to allow all components internal to the main housing to operate below their specified limits in the maximum ambient temperature. The main housing further comprises a plurality of slots for the coupling of a plurality of electronic modules to the main housing. The modules are connected to the main housing node through a module interface connector of the node. The electronic modules are system components of the main housing that control the electronic aspects of the optical node. The main housing further comprises a plurality of ports. The ports provide data connectivity between the optical node, the electronic modules and the distribution network.
In another aspect of the invention, the optical node is comprised of control interfaces for routing of the data of the distribution network over the optical and RF components of the optical node. Additionally, the optical node has an interface for the routing of power from the main power connector of the optical node to a plurality of electronic modules that comprise the optical node.
In another aspect of the invention, the optical node is comprised of a plurality of optical receiver modules, which receiver module receives information-modulated light from an optical fiber of the fiber management system and converts that information into an electrical signal for distribution over the data network.
In another aspect of the invention, the optical node comprises a plurality of optical transmitter modules, which transmitter modules convert electrical signals that originate primarily from the subscriber of the data services to information-modulated optical signals that are transported by optical fiber of the distribution network to a central location of the head end data service provider.
In another aspect of the invention, the optical node comprises a plurality of RF output modules, which RF output modules comprise the RF interface to the coaxial cable plant of the data distribution network via an AC/DC entry module and the main housing.
In another aspect of the invention, the optical node comprises at least one power supply module, which power supply module receives AC/DC electrical power for the optical node from the main cable or through a dedicated power line. The AC/DC power is converted to DC at regulated levels for distribution to any of the optical receivers, optical transmitters, and RF output modules deployed in the optical node.
In yet another aspect of the invention, return and transmit functions of the RF output, transmitter and receiver modules incorporate status monitoring for the purpose of controlling any of the plurality of the electronic modules via the external data cable and internally via the serial data bus of the optical node.
In yet another aspect of the invention, the optical node comprises at least one AC/DC entry module, which entry module provides the diplexing of the power and RF signals.
In still yet another aspect of the invention, the multi-port optical node comprises a uniform footprint of all modules. Thus, any module can be placed in any of the appropriate ports of the node.
In still yet another aspect of the invention, power supply modules can be added as needed to the optical node, including adding power modules to the node when the node has been activated on the distribution network.
In an alternative embodiment of the invention, there are two half-duplexed power supply modules of the optical node so that a plurality of power supply modules in parallel can power a plurality of electronic modules of the optical node.
In another aspect of the present invention, there is provided a system and method for monitoring and controlling electronic module functions via a synchronous serial data bus of the optical node firmware. In the preferred embodiment of the invention, the serial data bus consists of wired and bi-directional, data and clock lines. The lines are connected to an electronic module via a module connector on the module controller.